Tackifying resins are often used to modify various acrylic polymers to produce adhesive compositions. Traditional tackifier resins include, for example, rosins, rosin esters, colophonium-based resins, C5 and C9 based hydrocarbon resins, terpene-based resins, coumarone and indene-based resins, and phenolic resins. These tackifiers are used to produce, for example, pressure-sensitive adhesives and hot-melt adhesives.
Many of these commercial tackifiers cannot be used in certain applications. For example, in medical applications, some tackifiers cannot be utilized due to skin sensitivity concerns. The medical adhesive industry has a perception that rosins and rosin esters can cause skin sensitivity, therefore, rosins and rosins esters may not be used in this application.
In addition, tackifier resins used in many adhesive applications need to be clear and to not cause fogging. Also, tackifier resins may also need to not inhibit the breathability of an adhesive composition as indicated by the moisture vapor transport rate of the adhesive composition after the tackifier resin is added.
Therefore, there is a need in the adhesive industry for new tackifier. resins that can modify acrylic polymers and provide these properties.